不同高温胁迫对白桦幼苗几个生理生化指标和电阻抗图谱参数的影响

Physiological and Biochemical Indexes and Electrical Impedance Spectroscopy of Betula platyphylla Seedlings under Heat Stress

以白桦1年生实生苗为试材,分别用37℃与42℃高温处理2、4、8、122、4 h,以常温处理(白天25℃1、2 h/夜间15℃1、2 h)苗木为对照,对其叶片叶绿素含量、根系活力、可溶性糖含量、超氧化物歧化酶(SOD)活性、超氧阴离子(O2.-)含量、丙二醛(MDA)含量、蛋白质含量和电阻抗进行测定,研究其抗热性。结果表明:37℃处理的叶片中叶绿素含量低于对照,SOD活性和MDA含量高于对照;42℃处理的叶片中叶绿素含量、根系活力、可溶性蛋白含量、MDA含量和弛豫时间τ低于对照,SOD含量和胞外电阻(re)高于对照;并且42℃处理的叶片中叶绿素、可溶性糖、SOD活性高于37℃处理,而可溶性蛋白、O2.-、MDA含量和根系活力较37℃处理低。37℃下,胞内电阻(ri)与MDA含量呈显著正相关(r=0.68),β系数与可溶性糖含量呈显著负相关(r=-0.75),胞内电阻(ri)与可溶性蛋白含量呈显著正相关(r=0.75);42℃下,胞外电阻(re)与可溶性糖含量成显著正相关(r=0.91),胞内电阻(ri)与SOD活性成显著负相关(r=-0.51)。37℃与42℃处理下的电阻抗图谱参数差异显著,胞外电阻(re)、胞内电阻(ri)、弛豫时间τ和β系数变化规律不一致。研究发现,42℃是高温胁迫下诱导白桦幼苗抗热性的更理想条件;用电阻抗图谱法研究白桦幼苗的抗热性是可行的。

To study the heat tolerance of Betula platyphylla Suk.,chlorophyll content,root vitality,soluble sugar content,superoxide dismutaseon（SOD） activity,superoxide anion（O-·2） content,malondialdehyde（MDA） content,soluble protein content and electrical impedance spectroscopy（EIS） parameters were tested in leaves of one-year-old B.platyphylla Suk.seedlings.Heat stress temperatures of 37℃ and 42℃ were used with 2 h,4 h,8 h,12 h and 24 h treatment,respectively.Seedlings with 25℃,12 h（day）/15℃,12 h（night） were as control samples.The results indicated that under 37℃ treatment,chlorophyll content was lower,while SOD activity and MDA content were higher than those of the control.Under 42℃ treatment,chlorophyll content,root vitality,soluble protein content and relaxation time（τ） were lower,while SOD activity and extracellular resistance（re） were higher than those of the control.Under 42℃ treatment,chlorophyll content,soluble sugar content and SOD activity were higher,while soluble protein,O-·2,MDA content and root vitality were lower than those treated under 37℃.Under 37℃ treatment,there was a significant positive correlation between intracellular resistance（ri） and MDA content as well as a significant negative correlation between β and soluble sugar content.The ri and soluble protein content correlated positively.Under 42℃ treatment,extracellular resistance（re） significantly positively correlated with soluble sugar content,and ri significantly positively correlated with SOD activity.The changes of re,ri,relaxation time（τ） and β behaved differently between 37℃ and 42℃ treatments.In conclusion,the heat tolerance of birch seedlings tested by physiological and biochemical indexes suggests that 42℃ is an ideal condition to induce heat tolerance under high temperature stress compared with 37℃ treatment;and the EIS method is suitable for determining heat tolerance of birch seedlings.